在缩放模式图片框中平移矩形位置 [英] Translate Rectangle Position in Zoom Mode Picturebox

问题描述

我正在确定图像中的矩形区域，并在PictureBox中将其显示给用户.
由于图像有时可能非常大，因此我正在使用将SizeMode设置为Zoom的PictureBox.

I'm determining the rectangular area in an image and showing it to the user in a PictureBox.
Since the image can sometimes be very large, I'm using a PictureBox with its SizeMode set to Zoom.

我正在使用以下代码转换矩形(X，Y)坐标:

I'm using the following code to translate the Rectangle (X, Y) coordinates:

public Point TranslateZoomMousePosition(Point coordinates)
{
    // test to make sure our image is not null
    if (pictureBox5.Image == null) return coordinates;
    // Make sure our control width and height are not 0 and our 
    // image width and height are not 0
    if (pictureBox5.Width == 0 || pictureBox5.Height == 0 || pictureBox5.Image.Width == 0 || pictureBox5.Image.Height == 0) return coordinates;
    // This is the one that gets a little tricky. Essentially, need to check 
    // the aspect ratio of the image to the aspect ratio of the control
    // to determine how it is being rendered
    float imageAspect = (float)pictureBox5.Image.Width / pictureBox5.Image.Height;
    float controlAspect = (float)pictureBox5.Width / pictureBox5.Height;
    float newX = coordinates.X;
    float newY = coordinates.Y;
    if (imageAspect > controlAspect)
    {
        // This means that we are limited by width, 
        // meaning the image fills up the entire control from left to right
        float ratioWidth = (float)pictureBox5.Image.Width / pictureBox5.Width;
        newX *= ratioWidth;
        float scale = (float)pictureBox5.Width / pictureBox5.Image.Width;
        float displayHeight = scale * pictureBox5.Image.Height;
        float diffHeight = pictureBox5.Height - displayHeight;
        diffHeight /= 2;
        newY -= diffHeight;
        newY /= scale;
    }
    else
    {
        // This means that we are limited by height, 
        // meaning the image fills up the entire control from top to bottom
        float ratioHeight = (float)pictureBox5.Image.Height / pictureBox5.Height;
        newY *= ratioHeight;
        float scale = (float)pictureBox5.Height / pictureBox5.Image.Height;
        float displayWidth = scale * pictureBox5.Image.Width;
        float diffWidth = pictureBox5.Width - displayWidth;
        diffWidth /= 2;
        newX -= diffWidth;
        newX /= scale;
    }
    return new Point((int)newX, (int)newY);
}

在确定的位置添加框架控件:

Adding a frame control at the determined position:

pictureBox5.Controls.Clear();
var c = new FrameControl();
c.Size = new Size(myrect.Width, myrect.Height);
c.Location=TranslateZoomMousePosition(newPoint(myrect.Location.X,myrect.Location.Y));
pictureBox5.Controls.Add(c);

但是确定的帧/矩形位置不正确.
我在做什么错了?

But the determined frame/rectangle location is not correct.
What am I i doing wrong?

推荐答案

您可以通过以下方式将图片框上的选定矩形转换为图像上的矩形:

You can translate selected rectangle on the picture box to the rectangle on image this way:

public RectangleF GetRectangeOnImage(PictureBox p, Rectangle selectionRect)
{
    var method = typeof(PictureBox).GetMethod("ImageRectangleFromSizeMode",
        System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
    var imageRect = (Rectangle)method.Invoke(p, new object[] { p.SizeMode });
    if (p.Image == null)
        return selectionRect;
    var cx = (float)p.Image.Width / (float)imageRect.Width;
    var cy = (float)p.Image.Height / (float)imageRect.Height;
    var r2 = Rectangle.Intersect(imageRect, selectionRect);
    r2.Offset(-imageRect.X, -imageRect.Y);
    return new RectangleF(r2.X * cx, r2.Y * cy, r2.Width * cx, r2.Height * cy);
}

注意:您可以找到ImageRectangleFromSizeMode方法

Note: You can find ImageRectangleFromSizeMode method source code here and use it as write such method as part of your application code.

示例-具有SizeMode = Zoom的PictureBox的裁剪图像

作为示例，以下代码将裁剪图片框1的给定矩形，并将结果设置为图片框2的图像:

As an example, the following code will crop the given rectangle of the picture box 1 and will set the result as image of picture box 2:

var selectedRectangle = new Rectangle(7, 30, 50, 40);
var result = GetRectangeOnImage(pictureBox1, selectedRectangle);
using (var bm = new Bitmap((int)result.Width, (int)result.Height))
{
    using (var g = Graphics.FromImage(bm))
        g.DrawImage(pictureBox1.Image, 0, 0, result, GraphicsUnit.Pixel);
    pictureBox2.Image = (Image)bm.Clone();
}

这是输入图像:

这是结果:

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